Air jet cleaning and nozzle for use therefor



5 Sheets-Sheet 1 Sept. 9, 1958 J. A. Elm-"PLE A AIR JET CLEANING ANDNOZZLE FOR USEl THEREFOR Filed Dec. 22, 1953 Sept. l9, 1958 J. A.EINHIPLE 2,851,383

AIR JET CLEANING AND NOZZLE FOR USE THEREFOR Filed Dec. 22, 1955 5Sheets-Sheet 2- nauoconona annabee oo ...I-loo consonance.

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avsloccactaonlocooo iocoenleonoou Olnoonouooooouooo nonuooanocanunmvENToR JOHN A. EINHlPLE avm/fw ATTORNEY 2,851,383 AIR JET CLEANING ANDNOZZLE FOR USE THEREFOR Filed Dec. 22. 1953 Sept. 9, 1958 J. A. EINHIPLE5 Sheets-Sheet 3 R O T M E V m JOHN A EINHIPLE Y QJ/AW .ATTORNEY Sept.9, l1958 Filed Dec. 22, 1953 6 '14423, G 271'.' |42 gg. 43 21 J. A.`EINHIPLE AIR JET CLEANING 'AND NozzLE Fon us5: THEREFOR 5 Sheets-Sheet,4

JOHN A. EINHIPLE ATTORNEY Sept. 9, 1958 4 JQrElNHIPLE 2,351,383

AIR JET CLEANING AND NozzLE FOR USE.' rHgREFoR Filed Dec. 22, 1953 l "5Sheets-Sheet 5 k l JOHN A.EINHIPLE BY. im*

ATTORNEY AIR JET CLEANNG AND N OZZLE FOR USE THEREFOR ApplicationDecember 22, 1953, Serial No. 399,703 8 Claims. (Cl. 134-23) Thisinvention is in relation to nozzles for producing iiuid jets and isdirected especially to nozzles for producing a straight jet of air. Theinvention is more particularly directed to the cleaning out of cavitiesor holes, especially a great plurality of holes, such as are present indrilled acoustical tile.

One type of ceiling construction, which is now well known, includes asurface of a plurality of tiles of lowdensity wood iiberboard, thesurfaces of which are provided with a multiplicity of cavities orcylindrical holes for acoustical sound absorbing purposes. Variousmethods, such as drilling, cutting and punching, have been provided forproducing these holes in the tiles, the most common method beingdrilling. However, since the holes, as normally provided, extend only aportion of the distance through the thickness of tile, and since thetile is normally constructed or a material having a low density and ahigh yieldability, no practical method of drilling is known, as yet,capable of removing completely, from both the side and end surfaces ofthe hole, all of the material desired to be so removed. Nor is anymethod known for satisfactorily cleaning either the dust from drillingor the incompletely severed pieces of material from the hole.

Although improvements have been made in the means for producing theholes, a substantial percentage of undesired material remains in theholes decreasing the sound absorbing quality of the tile and to somedegree reducing the quality from an appearance standpoint. The idea ofusing jets of air to clean the holes is not new, however, nocommercially successful and complete cleaning has been produced by sucha method heretofore. It has now been found that a small, exceedinglystraight stream or jet, that is, one with a minimum of deflection of allparts of the stream from a parallel path, is required in order to cleanthe holes with air jets to a satisfactory degree. Only a straightcontinuous jet is capable of the tearing or cutting action that isnecessary to remove a satisfactory amount of the undesired material,since a high percentage of this material is still attached to somedegree to the tile body or hole wall. The removal even of loosematerial, such as dust, also requires a small diameter straight jetsince it is essential to avoid interference between the air entering andthe air leaving the holes. What attempts have been made, heretofore,using air to clean acoustical tile, have been completely unsatisfactoryin all respects.

Prior nozzles for producing air jets did not produce an air stream inwhich the air maintained a sufiicient parallel or straight path for asuticient distance above tearing action or to avoid mushrooming of thejet which prevents removal even of loose dust. Therefore,

cleaning of acoustical tiles, heretofore, has been accomplished byvariations of vibrating and/ or hitting the tiles, a very unsatisfactorymethod.

A principal object of the invention is to provide a greatly improvedmethod of cleaning drilled acoustical iiberboard tiles. Brieiiy, thismethod includes the steps of blowing into the holes, at or near theperiphery theref, a relatively straight fluid stream or jet of smallsecto provide theV Amired j States Patent tional diameter at asubstantially high velocity, and even further, blowing such jetssuccessively at a plurality of positions around the periphery of thehole.

A further object of the present invention is to provide a nozzle capableof producing the optimum in a straight jet of air, at least for a simpleone piece nozzle. Briefly, this is accomplished by constructing thenozzle in accordance with a certain ratio of dimensions as disclosedherein.

A still further object of the invention is to provide a machine foraccomplishing the abovesaid methods for cleaning acoustical tile.Briefly, this is accomplished by constructing, in suitable relation totile carrying means, a plurality of nozzles constructed in accordancewith the invention, directed toward the plane of travel of the tiles anddisposed so as to blow a straight jet of air into the holes at or nearthe periphery thereof. The blowing of the Vstraight jets successively ata plurality of positions around the periphery of a hole is accomplishedby a novel arrangement of nozzles relative to the direction of travel ofthe t-ile.

These and other objects and advantages will be apparent when consideredin connection with the following detailed description of the preferredembodiment of the invention and the accompanying drawings in which:

Fig. l is a side elevation of a tile cleaning machine built inaccordance with and embodying the invention.

Fig. 2 is a plan View of the machine of Fig. 1.

Fig. 3 is a sectional view of a portion of the machine of Fig. 2 takenon line 3-3, showing in section an acoustical tile passing therethrough.

Fig. 4 is an enlarged view similar to Fig. 3 except taken on line 4-4 ofFig. 2.

Fig. 5 is a diagrammatic perspective view of a block having a singleacoustical type hole showing theoretically the path of an air jet forcleaning the hole in accordance with the invention.

Fig. 6 is a diagrammatic sectional plan View taken on line 66 of Fig. 4,showing the theoretical positions of the nozzles and jets, relative to atile hole, at and about which the cleaning operation occurs.

Fig. 7 is a sectional View of a nozzle constructed in accordance withthe invention with symbols for designating critical dimensions.

General description Referring now to Fig. l, an acoustical tile cleaningmachine 10 is shown which is constructed in accordance with and embodiesthe invention.

A frame 13, consisting of legs 14, motor supports 1S, air tank supports16, roller supports 17, dust shield supports 18, tile loading tablesupports 19, and tile discharge roller `supports 29, provides the meansfor supporting the various elements of the machine A1t).

ln general, the machine includes two laterally spaced apart, lower,tile-supporting, long-length endless V-belts 2S for carrying, atop theupper reaches thereof, the lateral edges of drilled acoustical fberboardtiles T through the length of machine 10. Drilled holes H, in one faceof the tiles T passing through the machine, open downward and pass overthree air tanks 26 having a plurality of air nozzles 27 aimed upwardtherefrom. Two laterallyv spaced-apart, upper, long-length endlessV-belts 28 are disposed so that the bottom reaches thereof ride atop thelateral edges of moving tiles T through the length of machine 10, which,due to the weight of rollers 29 resting vertically on V-belts 28, holddown the tiles T in resistance to high pressure air jets from Positivevertical support and lateral positioning of the lower tile-supportingV-belts 25 and lateral positioning of the tiles T and upper V-belts 28are provided by two grooved elongated belt shoes 35 which are suspendedin nozzles 27.

position and afiixed to both the air tanks 26 and the roller supports17.

Air is supplied to tanks 26 from a manifold 36 through pipes 37. Drivepower for both lower and upper V-belts, and 28, is supplied by a motor3S supported on motorplate 39 by motor supports 15. Dust shields 45, 46,47, i8 and 49 enclose respectively the top, bottom, sides, front andrear of the central or cleaning portion of machine 10.

Tile driving elements Motor 38, by way of reducer 54, drives a rearlower V-belt sheave drum through chain 56, sprockets 57, 58 and shaft59. Shaft 59 is rotatably supported at each side of drum 55 in bearings60 which are mounted on the rearward pair of legs 14. Sheave drum 55 hasannular belt grooves 61, one adjacent each lateral edge thereof, shapedcomplementarily for the reception of lower V-belts 25. A similarlyconstructed, forward, lower sheave drum 62, with belt grooves 63 for thereception of the opposite extent of lower V-belts 25, is affixed toshaft 64. Shaft 64 is rotatably mounted at end of drum 62 in bearingblocks 65. Blocks 65 are grooved along the top and bottom edges thereoffor mounting slidably betwecn flanged block supports 66, 67, which inturn are firmly mounted on side plates 68 supported by loading tablesupports 19.

Blocks 65 are slidably adjustable rearward and forward, to adjust thetension on lower V-belt 2S, by means of threaded shaft 69 fixed thereto,extending rearward therefrom, each through one of the forward legs 14,and threaded in lock nuts 70 which are tightened thereon against legs14. A cross member tile loading table 71, in the form of a plate orangle iron, extends across the frontmost portion of the machine, at avertical height even with the upper reach of the lower V-belts 25.

Also aiiixed on shaft 59 is driver spur gear 75 which engages drivenspur gear 80. Gear is affixed on shaft 81, which is rotatably supportedin bearings 82 mounted on the rearward pair of legs 14 above bearings60. Rearward upper sheave drum 83, also similar to the two lower sheavedrums, is afiixed on shaft 81, and has belt grooves 84 for the receptionof upper V-belts 28. A forward upper sheave drum 85, also similar to theaforesaid sheave drums, having belt grooves 86, is affixed on shaft 87which is rotatably supported by adjustably mounted bearings 88. BearingsS8 are mounted on a roller support extension 89 having elongated grooves90 to provide the adjustability in positioning bearings 88, thusproviding means for adjusting the tension on upper V-belts 23. A narrowcover sheet or guard 91 is disposed over the spur gear 80 and extendsback over the driving mechanism for the take-off rollers describedherebelow.

Also mounted and atiixed on shaft 59 is a chain drive sprocket 93 whichdrives tile discharge rollers 94 by means of chains 95 and sprockets 95.The sprockets 96 are atlixed on discharge roller shafts 97 which arerotatably supported in bearings 98 mounted on discharge roller supports20. The discharge rollers receive and carry the tile T from the workingportion of the machine and any number of such rollers may be provided inaccordance with the invention.

Referring now to Fig. 3; an enlarged sectional view, taken on line 3-3of Fig. 2, shows clearly the relation of certain above described partsat a position within the working or cleaning portion of the machine, itbeing understood that the opposite side of the machine is constructedsubstantially the reverse of Fig. 3. A lower V-belt 25 is shown slidablysupported and laterally positioned by the elongated belt shoe 35. Thebelt shoe is supported and fixed relative to the air tanks 26 by Lclamps 99, each L-clamp being bolted to one side of an ait tank andbolted to the bottom side of the shoe 35. For even greater stability ofthe belt shoes, several braces 100, of suitable cast angle strips, arebolted to the roller support 17 portion of frame 13 and bolted to theside face of shoes 35.

A complementary groove 101, for the reception of belt 25, extendsthroughout the length of a lower protruding portion 102 of shoe 35, theprotruding portion 102 being disposed beneath the lateral edge of tilesT as the tiles pass through the machine, so that the two opposite belts25 (only one shown in Fig. 3) are spaced apart and extend immediatelyalong the edges of the tiles T with a substantial portion thereunder forsupport. It will be apparent that the above said extreme wide spacingbetween opposite belts 25 would not be necessary if the holes H of thetiles to be cleaned were not disposed in such close proximity to thetile edges.

Each belt shoe 35 also includes an upper tile positioning protrusion 103extending throughout the length of each shoe, the spacing between theprotrusions 103, of each of the opposite side shoes 35, being the exactwidth of the tiles T, the arrangement being that the tile edges slidealong the inner faces 104 of protrusions 103 so that the tiles are heldsquare and laterally positioned in the machine. It will also be seen, inFig. 2, that the front ends 105 of protrusion 103 are tapered outward toprovide sufficient guiding means to bring into alignment tiles slightlymisguided in being fed into the machine. Guides 106 may also be providedon the loading table 71 to laterally position tiles T as the tiles arefed into the machine 10.

Referring again to Fig. 3, the disposition of the lower reach of one ofthe two upper V-belts 2S is shown, the outer edge of which slides alongthe inner face 104 of shoe protrusion 103, as does the edge of tile T.The upper reach of belt 2S and the lower reach of belt 25, in Fig. l,may be unsupported.

Rollers 29, extending axially across the machine and normally resting onthe two lower reaches of upper V-oelts 28, are maintained in respectivelongitudinal positions in the machine 10 by a series of interlocking,vertieally-free linkages 110 (Figs. l, 2, 3). Each link 110 includes aninverted L-extension 111 extending upward and then outward, and a crossbar 112 extends between upper-faces of extensions 111 of correspondingopposite laterally disposed links to maintain the lateral alignment ofthe linkages. A bolt 113, threaded through the adjoining portions ofextension 111 and cross bar 112, ex tends downward a distance exactlythat necessary to ccntact the roller support 17 to prevent rollers 29from hitting and misaligning shoe 25 which would otherwise occur in theabsence of a tile T at the point below the roller 29.

Tile Cleaning elements For the purpose of more clearly understanding thepresent embodiment, as shown and described, the description will bedirected to a machine for cleaning a tile of one particular form anddimension. The machine 10, in Figs. 1 and 2, is constructed to cleantiles T which are l2 inches square, having 484 holes H, of fr, inch(.l87") diameter, cut, drilled or punched partially therethrough in 22rows of 22 holes spaced evenly 1/2 inch apart, center to center,throughout the area of the tile with the exception of an edge portion ofapproximately 1/2 inch therearound. Thus in the machine iii, as shown,approximately three l2 inch tiles would be within the machine betweenlegs 14 at any given time. The above dimensions are included herein onlyto provide ease in visualizing and understanding the instant embodiment,it being understood that the invention is in no way limited to the sizesof tiles T, spacing of holcs H and could be widely varied as to size ofmachine 10.

The tile cleaning operation is accomplished, as previously discussed, bya great plurality of small, straight, jets of air of relatively highpressure and high speed. ln accordance with the invention, three airtanks 26 are disposed in spaced positions along and below the path oftravel of tiles T. In order to provide suitable removal of the dustcontaining or polluted air, a spacing in the order of at least six totwelve inches between air tanks should be maintained.

Air, under a pressure of thirty pounds per square inch, is supplied tothe air tanks 26 through pipes 37. In order to avoid excessiveturbulence of the air in the air tanks and pipes, it is necessary thatthe air tanks and pipes be of sufficient volume to provide air at anequal rate to all the nozzles 27.

In the present embodiment, a tank having a size of 3 x 3 x 12" and apipe having a l inside diameter is preferred. A valve 120 in manifold 36is provided for stopping air flow to tanks 26 at the completion ofoperation. Any standard air supply system (not shown), capable ofproviding 30 p. s.4 i. air, supplies air to the high pressure air inlet121.

A full top view of only the middle of the three tanks 26 is shown inFig. 2, it being understood that all three tanks are constructedsimilarly. The tanks 26 are bolted onto cross plates 125 which, in turn,are bolted to air tank supports 16 of frame 13. The air tanks consist ofa bottom plate 127, side plates 128, end plates 129 and a top plate 130,all welded at the junctions to provide a unitary, air tight box-likestructure. Tanks 26 are bolted to plates 125 by means of angle irons 131welded to the bottom edge of each end plate 129. Air pipe 37 terminatesat a complementary hole 135 in one end plate 129 and an air sealing weldis made thereabout.

In the top plate 130, eighty-eight holes 136, 5%6 inch in diameter areprovided for the reception of nozzles 27. Nozzles 27 are constructed inthe order of .005 inch greater diameter than holes 136 so that an airseal is provided by the inherent pressure of the press iit therebetween.The holes 136, and thus the nozzles 27, are disposed in four rows 137,namely 137, 137', 137, 137' of 22 nozzles each, the rows 137 extending90 to the direction of tile'travel, the arrangement being that eachnozzle in any one row directs a jet of air successively at holes H ofone lengthwise row of tile holes H as the tiles pass thereover, asdiscussed further herebelow.

Referring now to Fig. 3, and particularly Fig. 4, it will be seen thatsuccessive nozzles 27, 27', 2'7", 27 in successive rows 137, 137', 137,137'" are progressively displaced laterally in the order of .05 inchfrom the direction of travel of tiles T, the arrangement being that eachsuccessive nozzle 27, 27', 27, 27 of any one tank 26 directs a jet at alaterally progressively different zone of the holes H of the tiles T.

The theory behind the successful cleaning in the present inventio-n,which is based on the results of considerable testing, is that jets ofair are needed of greatly improved uniformity and straightness, whichwill not merely mushroom within hole H, but will instead, form andmaintain a uniform U-shaped path up one Wall and across the hole bottomface and down the opposite wall for that fraction of a second that thejet is directed toward a zone within and near the wall of the hole H.For a diagrammatic example, Fig. 5 shows a fictitious block 138, whichis no part of machine or tile T, and an air jet 139, the path of jet 139showing the form of the above described U-shaped path which is createdin the holes H of the tiles T.

From Figs. 4 and 6 it will be apparent that nozzles 27 and 27 will, whendirected toward hole H, always be directed towards a zone of the hole Hat or near the side wall of the hole, and thus will each have what mightbe described as one cleaning station, that is, they will set up, each atits own respective time, one uniform jet or U-shaped path of air goingupward into the hole at the zones designated u and y res ectively inFig. 6 and coming down the opposite wall, whereas nozzles 27 and 27"will each set up two dilferent jets in each hole, one upon being sopositioned that the jet is entering the hole area, v and x respectively,and one just before the jet is leaving the hole area, w and zrespectively. Thus, theoretically, there are six stations whereatl eachhole is cleaned, without actually any stopping thereat, in the course ofthe progress of the hole over any one tank 26. The six stations aredisplayed diagrammatically in Fig. 6, all on one hole simultaneouslyalthough it will be apparent that only one such station would bereceiving the air jet at any one time. Thus, considering the portion oftile shown in Fig. 6 as traveling downward, and that shown in Fig. 4traveling into the paper, the chronological progression of the stationsbeing cleaned would be first at Lt as hole H is over nozzle 27, at v ashole H first comes over nozzle 27', at w as hole H is about to pass fromover nozzle 27', at x as hole H first comes over nozzle 27, at z as holeH is about to pass from over nozzle 27, at y as hole H is over nozzle27.

As was previously stated, the diculty encountered in cleaning thedrilled, cut or punched holes of acoustical tile is unusually greatbecause the material to be cleaned therefrom is oftentimes a unitary,not completely separated portion of the tile material, attached to somedegree to the hole wall. A mere turbulence of air in the hole, whichwould be created in the form of a mushrooming of air if the jet of airwere not straight, parallel and uniform, would not provide the cuttingtype of action required to sever attached but undesirable material. Astraight jet proyides a cutting action which is suitable for the removalof such attached material.

Therefore, a nozzle is required, which is simple and small, due to thegreat number required, which is capable of producing a straight anduniform jet of air. It is readily appreciated that no nozzle couldprovide a jet of air in which the air proceeded through other than a astraight and parallel course.

provided herein which far surpasses known nozzles in dispensing theoptimum in straight jets of air. In Fig. 7, a single nozzle 27 is shownin section with critical dimensions designated thereon. Nozzle 27includes a long, large bore air inlet or port having a diameter d and anoverall length c and a small air outlet or port 141 coaxial with port140 with diameter a and length b, ports 140 and 141 forming a continuousduct through nozzle 27. 1n the preferred embodiment, the criticaldimensions of nozzle 27 are:

However,

It has also been found that the size of the nozzle may be varied widelyso long as the dimensions a, b, c and d are always variedproportionately from the above dimensions. Very little, if any,variation in diameter of outlet 141 throughout its extent can bepermitted. The dimension c, hereabove, is the least critical, and couldbe reduced considerably if larger tanks 26 or other means for preventingturbulence were provided. The preferred conical angle a at the innermostextent of inlet 140 is in the order of 30 from the perpendicular or inthe order of 60 to the axis and would remain in the order of 60 for allvariations in size of the nozzle in accordance with the invention. Theallowable variation in this angle has been found to be in the order ofplus or minus 10 to provide the optimum straight jet.

The distance between the tips 142 and the face of the passing tile T(Fig. 4) is a further critical dimension for the optimum cleaningeciency. For the particular embodiment of the invention disclosed above,a spacing in the order of 1A inch is required. For larger tile holes, alarger nozzle and a greater spacing between nozzle and tile would bepreferred. If the nozzle is too close to the tile, a restriction iscreated against air leaving the hole. If the spacing is too great, thehole is not cleaned eificiently to the full depth thereof. Furthermore,a frusto-conical nozzle end 143 is essential to avoid deflecting aircoming from the hole H into the upward traveling air jet entering thehole H.

It has been stated that three similar tanks 26 are provided in spaceddispositions along the direction of tile travel. Less tanks may beprovided and the tile travel speed proportionately slowed, however, thequality of the cleaning is decreased considerably. Undoubtedly, thisquality would not be so substantially decreased by the use of one tank,if the same number and arrangement of nozzles were included as are abovedescribed as included in the three tanks, however, such a constructionwould not have the preferred improved susceptabiliy to removal of dustprovided by three spaced apart tanks. It will also be apparent that theoptimum number of tanks is also dependent on the elliciency of the meansemployed for drilling, cutting or punching the holes and on the cohesivestrength of the material of the tile and thus the difficulty of removingundesired portions. The use of a higher air pressure with a lessernumber of tanks has been found to provide the def-'red quality incleaning, however, with the tiles made from the materials preferredtherefor, excessive cutting and tile damage is caused by the excessivelyhigh speed, straight air jet.

Dust removal elements The removal of dust-filled air from the machine,although not a part of the invention, is necessary in order to provide aproperly over-all cleaned product, as well as to provide suitableworking conditions in the vicinity of the machine.

Suitable sheet metal shields 45, 46, 47, 4S and 49 are constructed toenclose the central working portion of the machine 10. Top and bottomshields 45 and 46 are shown by broken lines in Fig. l, and areformed'pyramidi- 5"' cally, tapering to an upper dust outlet 145 and alower dust outlet 146. High volume suction pumps (not shown) draw thedust-laden air from both outlets 145 and 146. The construction of theassembly of dust shields is not air tight, but instead has sufficientallowancel for air intake at joints and at ports cut out therefrom forfitting about working parts of the machine which extend through theshields.

Operation The specific operation of the individual elements is discussedabove and considered to be understandable therefrom. The operation, ingeneral, of machine 1t), includes starting of motor 38, opening airvalve 120, starting dust removal fans (not shown) and providing, by handor other means, feeding of tiles T onto loading table 71 and onto lower\{belts 25. Tiles T are fed into machine 10 with the holes H openingdownward and upper and lower V-belts ZS-and Z5 cause the tiles toprogress through the machine, and be discharged onto rollers 94. Meanswill need be provided, hand means or otherwise, for removing dischargedtiles` from rollers 94.

Air pressure supplied to tanks 26 causes a straight jet of air to bedirected upwards from each 4of the 264 nozzles 27 (4 rows of 22 nozzlesin each of three tanks). Each of the 22 nozzle-s 27 in each of thetwelve rows correspond and act "h corresponding nozzles of all otherrows 137 respectively on one of the 22 holes H in each of the 22transverse rows of holes in cach tile T. Thus each hole H is acted o-nby l2 nozzles, however, the first respective nozzle encountered on eachtank by any given hole H is displaced transversely relatively to oneside of the hole, the second nozzle is relatively adjacent but to oneside of the center of the hole, the third nozzle is relatively adjacentbut to the opposite side of the center of the hole, and the fourthnozzle encountered is relatively .isplaced to the side of the holeopposite to that to which the first nozzle is relatively displaced. Thusthe straight jets of air from the respective nozzles enter the holes Hat the same relative locations and perform the cleaning by the cuttingaction of a non-mushroomed flow of air which will occur when the jetsare entering the hole H at approximately any of the six stations u, v,w,

x, y or z shown in Fig.' 6. A complete cycle, of cleaning at each of thesix lstations would occur three times, once 0 at each tank 26. Aftercompletion of three such cycles on the holes H of a fiberboardacoustical tile T, substantially all undesirable material has been foundto be removed.

Having, thus, completed a detailed description of a l() preferredembodiment of the invention so that those skilled in the art maypractice the same, l. contemplate' that variations may be made withoutdeparting from the scope of the invention as defined in the appendedclaims.

I claim:v l. A nozzle for producing the optimum straight jet of rdmaterial, comprising a large port and a small port coaxial therewith,said ports forming a continuous duct through said nozzle, said smallport having a diameter a A and a length b, said large port having adiameter d, said Z0 dimensions having a ratio in the order ofa:b:d:.032: .l:.l25, and the inner transverse end of said large porthaving a frusto-conical taper in thc order 60 to thc axis of saidnozzle. g 2. A nozzle for producing the optimum straight jet of 2O fluidmaterial for cleaning undesired material from cavities, comprising afrusto-conical fluid outlet end, a large port, a small port coaxialtherewith, said ports forming a continuous duct through said nozzle,said small port having a diameter a and a length b, said large porthaving a diameter d, said dimensions having a ratio in the order ofa:b:d=.032:.l25:.l25, and the inner transverse end face of said largeport having a frusto-conical taper in the order 60 to the axis of saidnozzle.

3. In combination, a nozzle and air tank for producing the optimumstraight jet of air comprising a nozzle having a large port and a smallport coaxial therewith, said ports forming a continuous duct throughsaid nozzle, said small port having a diameter a and a length b, saidlarge port having a length c and a diameter d, said dimensions having aradio in the order of a:b:c:d=.032:.125 at least .8752.125, the innertransverse face of said large port having a conical taper in the order60 to the axis of said nozzle, said nozzle being affixed to and openingat the large diameter port end into an air tank, said air tank having ahollow, interior air reservoir of sufficient volume to eliminateturbulence in the supply air under pressure. 4. The method of cleaningacoustical tile having a plurality of cavity type sound absorbing holestherein, comprising the steps of successively blowing a straight,parallel jet of air into said holes at a plurality of stations, said jetentering said holes at each of said stations adjacent the periphery ofsaid holes and spaced from the center of said holes allowing said jet totravel into said holes at each said station, thence across the end ofsaid holes to the opposite portion of periphery, thence outward of saidholes along said opposite portion of periphery.

5. The method of cleaning acoustical tile having a plurality ofcavity-type sound absorbing holes therein G0 comprising the steps ofsuccessively blowing a straight, parallel jet of air into said holes ata plurality of stations, said jet entering said holes at each of saidstations adjacent the periphery of said holes and spaced from the centerof said holes allowing said jet to travel into said G5 holes at eachsaid station, thence across the end of said holes to the oppositeportion of periphery, thence outward of said holes along said oppositeportion of periphery, positioning said tiles relative to said jet of airat successive stations by passing said tile in front of said -iet in adirection perpendicular to said jet, systematically laterally displacingsaid tile relative to said jet in each successive pass.

6. The method of cleaning acoustical tile having a plurality ofcavity-type sound absorbing drilled holes therein, comprising the stepsof passing said tiles perpendicularly through a straight jet of airbeing blown from a straight-jet nozzle, disposing said straight-jetnozzle close enough to the drilled face of said tile that the air jetenters said holes in a substantially straight parallel path but not soclose that air leaving said cavity is deflected by said nozzle into saidentering air jet, disposing said nozzle so that the entering air jet isat a given zone adjacent the cavity periphery, maintaining the air jetdiameter so that the entering air stream is spaced from the center ofsaid holes so that the air jet is caused to follow a path into the holesin a direction generally toward the depth of the holes at said givenzone, thence across the bottom of said holes to a zone opposite saidgiven zone, thence outward from said holes at said opposite zone.

7. A machine for cleaning acoustical tile having a plurality ofcavity-type sound absorbing holes therein, said machine comprising anair tank, a plurality of straight-jet producing nozzles disposed in oneface of said tank, said tank having sucient volume to providesubstantially equal air pressure to all said nozzles, belt shoesextending through the cleaning portion of said machine, endless beltsdisposed in said shoes for supporting and advancing said tiles throughsaid machine and for positioning said tile holes successively overrespective nozzles, said shoes and thus said belts being laterallyspaced apart and disposed under the edges of tiles being supportedthereon, and spaced from said holes of tiles supported thereon, andmeans for restraining said tiles against movement away from saidnozzles, said nozzles being constructed to produce a straight jet of airhaving a diameter less than half the diameter of said holes, to providea jet capable of entering said holes adjacent the periphery of saidholes and follow a substantially U-shaped path into and thence out ofsaid holes in a continuous, substantially uniform stream.

8. A machine for cleaning acoustical tile having a plurality ofcavity-type sound absorbing holes therein, said machine comprising anair tank, a plurality of nozzles disposed in one face of said tank, saidtank having sucient volume to provide substantially equal air pressureto all said nozzles, belt shoes extending through the cleaning portionofsaid machine, endless belts disposed 1.0 in said shoes for supportingand advancing said tiles through said machine and for positioning saidtile holes successively over respective nozzles, said shoes and thussaid belts being laterally spaced apart and disposed under the edges oftiles being supported thereon and spaced from said holes of tilessupported thereon, and means for restraining said tiles against movementaway from said nozzles, said nozzles having a large port and a smallport coaxial therewith, said ports forming a continuous duct throughsaid nozzles, said small port having a diameter a and a length b, saidlarge port having a length c and a diameter d, said nozzle dimensionshaving relative values one to another in the order of the innertransverse end face of said large port having a truste-conical taper inthe order of to the axis of said nozzle, and the spacing between saidnozzle and the adjacent face of said tiles having a relative value withrespect to the other said relative values in the order of .250.

References Cited in the file of this patent UNITED STATES PATENTS1,018,046 Goldman Feb. 20, 1912 1,280,731 Herr Oct. 8, 1918 1,281,005Herman Oct. 8, 1918 1,310,107 Zouck July 15, 1919 1,360,265 Capell Nov.30, 1920 1,448,255 Capell Mar. 13, 1923 1,462,512 Loew July 24, 19231,524,851 Wolf Feb. 3, 1925 1,545,253 Hall July 7, 1925 1,711,429 SennApr. 30, 1929 2,231,136 Newey Feb. 11, 1941 2,538,445 Derbenwick Jan.16, 1951 2,633,437 Detjen Mar. 31, 1953 2,660,513 Ball Nov. 24, 19532,734,213 Ashford Feb. 14, 1956 FOREIGN PATENTS 39,770 Denmark Feb. 4,1929

4. THE METHOD OF CLEANING ACOUSTICAL TILE HAVING A PLURALITY OF CAVITYTYPE SOUND ABSORBING HOLES THEREIN COMPRISING THE STEPS OF SUCCESSIVELYBLOWING A STRAIGHT, SAID JET ENTERINGG SAID HOLES AT EACH OF SAIDSTATIONS ADJACENT THE PERIPHERY OF SAID HOLES AND SPACED FROM THE CENTEROF SAID HOLES ALLOWING SAID JET TO TRAVEL INTO SAID HOLES AT EACH SAIDSTATION, THENCE ACROSS THE END OF OUTHOLES TO THE OPPOSITE PORTION OFPERIPHERY, THENSE OUTWARD OF SAID HOLES ALONG SAID OPPOSITE PORTION OFPERIPHERY.
 7. A MACHINE FOR CLEANING AROUSTICAL TILE HAVING A PLURALITYOF CAVITY-TYPE SOUND ABSORBING HOLES THEREIN, SAID MACHINE COMPRISING ANAIR TANK, A PLURALITY OF STRAIGHT-JET PRODUCING NOZZLES DISPOSED IN ONEFACE OF SAID TANK, SAID TANK HAVING SUFFICIENT VOLUME TO PROVIDESUBSTANTIALLY EQUAL AIR PRESSURE TO ALL SAID NOZZLES, BELT SHOESEXTENDING THROUGH THE CLEANING PORTION OF SAID MACHINE, ENDLESS BELTSDISPOSED IN SAID SHOES FOR SUPPORTING AND ADVANCING SAID TILES THROUGHSAID MACHINE AND FOR POSITIONING SAID TILE HOLES SUCCESSIVELY OVERRESPECTIVE NOZZLES, SAID SHOES AND THUS SAID BELTS BEING LATERALLYSPACED APART AND DISPOSED UNDER THE EDGES OF TILES BEING SUPPORTEDTHEREON, AND SPACED FROM SAID HOLES OF TILES SUPPORTED THEREON, ANDMEANS FOR RESTRAINING SAID TILES AGAINST MOVEMENT AWAY FROM SAIDNOZZLES, SAID NOZZLES BEING CONSTRUCTED TO PRODUCE A STRAIGHT JET OF AIRHAVING A DIAMETER LESS THAN HALF THE DIAMETER OF SAID HOLES, TO PROVIDEA JET CAPABLE OF ENTERING SAID HOLES ADJACENT THE PERIPHERY OF SAIDHOLESAND FOLLOW A SUBSTANTIALLY U-SHAPED PATH INTO AND THENCE OUT OFSAID HOLES IN A CONTINUOUS, SUBSTANTIALLY UNIFORM STREAM.